Reply With QuoteMy 79 Hawaiian does not have a waterpump, the water is pumped in through the jet. P.S. there is no such thing as a dumb question except the one that doesn't get asked.
I know this is a dumb question but, do jet boat have water pumps, or is the jet drive the "water pump"? I'm asking because I've seen a lot of people on here talk about having too much water pressure and it got me thinking that if the jet supplies that much water to the engine, do they need water pumps. Thanks for putting up with my stupidity. I lean more and more each day from this site!
My 79 Hawaiian does not have a waterpump, the water is pumped in through the jet. P.S. there is no such thing as a dumb question except the one that doesn't get asked.
Ok, thats what I thought. Thanks! I've heard of a waterpump blockoff plate. Is that what's there instead?
This depends on the engine setup. Most older jets do not have crank-driven water pumps. The engine is fed from the bowl. However, newer engines, specifically those outfitted to aluminum jet boats (the fishing type... fishrite, northriver, etc) have a closed cooling system. In a closed cooling system the jet pump feeds water to a heat exchanger and is dumped out the exhaust. A crank-driven water pump circulates antifreeze through the engine and to the heat exchanger, so no lake/river water ever goes through the engine.
The water pump holes arent blocked off, but have fittings to attach hoses too...
The pump feeds the water to the engine. I have a bypass valve that is adjustable and alows the excess water to escape eliminating the risk of blowing a gasket.
On my 74 w/ olds, I have a feed from the jet to a housing on the water neck(which is the "out" of the engine). This water neck housing has a large hose that goes to the inlet of the crank driven water pump, and two hoses that feed the water to the exhaust.
Basically, the water from the jet pump hits the top of the engine where it is mixed with water being circulated through the block. Any excess is put out to the exhaust.
The water pump in this case is more of a circulating device than a true pump.
On those without a water pump and jet driven only - how does the engine get water at idle? Is there still enough pressure to fill the block?
If you are going to do it from scratch today and you have your choice - which one would you choose?
Yes, the engine still gets plenty of water at idle. When sitting still, the pump is still flowing plenty of water, it just flows equally front and back. With no thermostat my engine temp will rise to 110 at idle, but no more. On my engine, which has log & snail exhaust, the water comes from the pump, through the logs to preheat it, then to the engine, then to the snails and out through the exhaust...
Yes, the engine still gets plenty of water at idle. When sitting still, the pump is still flowing plenty of water, it just flows equally front and back. With no thermostat my engine temp will rise to 110 at idle, but no more. On my engine, which has log & snail exhaust, the water comes from the pump, through the logs to preheat it, then to the engine, then to the snails and out through the exhaust...
Thats almost how mine was plumbed.
Mine came from the pump. To the headers to pre heat. Out the headers to the water pump holes. Out the thermostat housing to the risers, then out the tips.
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